In recent years, several technologies have been proposed to control a variety of devices from remote sites via the Internet. (Refer to Patent Literature 1.) Such control over the devices via the network such as the Internet requires assignment of a unique identification number, such as a global IP address, to each of the controlled devices in order to allow the server to directly control the devices. Since the number of unique identification numbers assigned to the controlled devices is finite, available unique identification numbers would be exhausted once all the controlled devices are each assigned with a unique identification number.
To address this, a technology has been proposed for controlling devices via a network such as the Internet. (Refer to Patent Literature 2.) In the proposed technology, a local controller accesses a server to retrieve control instructions from the server and controls the devices in accordance with the retrieved control instructions. This configuration, in which the local controller controls the devices by acquiring the control instructions through polling, eliminates the need for assignment of a unique identification number to each device.